The present invention relates to a package for non-aqueous electrolytic battery. More particularly, the present invention relates to a package for non-aqueous electrolytic battery which can prevent water from invading externally and strength from decreasing over the long term and lengthen life and heighten reliability of the battery, and relates to a non-aqueous electrolytic battery whose life is lengthened and reliability is heightened by using said package.
Downsizing and weight saving of batteries are needed for smaller and lighter portable electronic devices. Lithium ion batteries are regarded as the most suitable secondary battery for achieving the object because of the high voltage and high energy density, and are being actively upgraded. One of the important points for the upgrade of the battery is to replace recent metal outer housing of the battery with a lighter package comprising a film such as an aluminum laminated film or the like. Such a package comprising a film is prepared by thermal melting and adhesion of a part of a folded film covering a battery content, and is formed like a bag.
Compared to the currently used metal outer housings, these packages comprising films have inferior blocking against water invading into a battery and insufficient strength because of its adhesion part, which possibly causes troubles with long-term battery performance or reliability in high temperature.
The present invention has been carried out in order to solve the above problems. The object of the present invention is to provide a battery package for a non-aqueous electrolytic battery such as lithium ion batteries, using a laminated film, by which water blocking is ensured and strength is maintained easily for a long time, and to provide a battery using the same.
As a means for improving the reliability of these packages, there are, for example, a process for maintaining credible sealing by laminating a protective film at a heat-sealed part as shown in Japanese Unexamined Patent Publication No. 40114/1999 and a process for maintaining credible sealing by constructing a heat-sealed part with a plurality of resins, i.e., a material having superior barrier performance against electrolyte and a material having excellent vapor barrier performance as shown in Japanese Unexamined Patent Publication No. 274896/1997. However, these processes have problems with increase of package weight and complicated steps.
The present inventors have found some important facts about water blocking and durability of adhesion strength concerning a package for a non-aqueous electrolytic battery using a laminated film. It was found that a trace of reactive substance diffused into the adhesion layer from the package interior side, leading to decrease of water blocking and adhesion strength of the package. The reactive substance in a trace quantity seems to comprise substance separated from electrolytic salt such as acid including hydrogen fluoride, or PF5. Diffusion of the substance causes deterioration of the adhesion layer or an aluminum layer, resulting in decrease of water blocking performance and adhesion strength. The laminated film can hold a structure capable of reacting with or absorbing a diffusing element to inhibit the diffusion from the battery interior. However this process causes unfavorable phenomena such as decrease in adhesion strength and increase in water diffusion from outside. Prevention of the diffusion from the battery interior without affecting performance of the adhesion part is highly effective in improving package performances.
More specifically, the present invention relates to: a package for non-aqueous electrolytic battery, having a bag construction to store a battery content made by adhesion of a part of a lamination film comprising a metal layer and a resin layer, wherein the adhesion part holds a structure capable of reacting with or absorbing an element which diffuses from battery interior inwardly to the battery interior side; the package for a non-aqueous electrolytic battery, wherein adhesion of the film is performed by using a hot-melt adhesive in the form of tape containing a structure capable of reacting with or absorbing A an element which diffuses from battery interior; the package for a non-aqueous electrolytic battery, wherein adhesion of the film is performed by a hot-melt adhesive in the form of tape containing, in parallel to the longitudinal direction, a filament structure capable of reacting with or absorbing an element which diffuses from battery interior; a battery using the package for a non-aqueous electrolytic battery.